The VLT LEGA-C spectroscopic survey : the physics of galaxies at a lookback time of 7 Gyr

Abstract

The Large Early Galaxy Census (LEGA-Ca) is a Public Spectroscopic Survey of ∼ 3200 K-band selected galaxies at redshifts z=0.6-1.0 with stellar masses M* > 1010M_sun, conducted with VIMOS on ESO's Very Large Telescope. The survey is embedded in the COSMOS field (R.A. =10h00; Dec.=+2deg). The 20-hour long integrations produce high-S/N continuum spectra that reveal ages, metallicities and velocity dispersions of the stellar populations. LEGA-C's unique combination of sample size and depth will enable us for the first time to map the stellar content at large look-back time, across galaxies of different types and star-formation activity. Observations started in December 2014 and are planned to be completed by mid 2018, with early data releases ofthe spectra and value-added products. In this paper we present thescience case, the observing strategy, an overview of the data reduction process and data products, and a first look at the relationship between galaxy structure and spectral properties, as it existed 7 Gyr ago.